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CVE-2026-27729

Estado: AnalizadaAlta (7.5)—

Astro is a web framework. In versions 9.0.0 through 9.5.3, Astro server actions have no default request body size limit, which can lead to memory exhaustion DoS. A single large POST to a valid action endpoint can crash the server process on memory-constrained deployments. On-demand rendered sites built with Astro can define server actions, which automatically parse incoming request bodies (JSON or FormData). The body is buffered entirely into memory with no size limit — a single oversized request is sufficient to exhaust the process heap and crash the server.

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Astro's Node adapter (`mode: 'standalone'`) creates an HTTP server with no body size protection. In containerized environments, the crashed process is automatically restarted, and repeated requests cause a persistent crash-restart loop. Action names are discoverable from HTML form attributes on any public page, so no authentication is required. The vulnerability allows unauthenticated denial of service against SSR standalone deployments using server actions. A single oversized request crashes the server process, and repeated requests cause a persistent crash-restart loop in containerized environments. Version 9.5.4 contains a fix.

CVSS

Probabilidad de explotación (EPSS)

EPSS (Exploit Prediction Scoring System, de FIRST) estima la probabilidad de que una vulnerabilidad sea explotada en 30 días. Complementa a CVSS (impacto) y a CISA KEV (explotación confirmada).

🎯 Técnicas ATT&CK

Cómo se explota esta vulnerabilidad y qué consigue el atacante, en el lenguaje de MITRE ATT&CK.

Vector CVSS AV:N/AC:L/PR:N/UI:N indica explotación remota sin autenticación (T1190). El DoS por agotamiento de memoria en el servidor via POST sin límite de tamaño es T1499.004 (Application Exhaustion).

Inferido por nuestro agente de análisis a partir de la descripción oficial, el vector CVSS y la CWE, y comprobado por un supervisor. Puede contener errores.

🛡️ Mitigaciones ATT&CK que cubren estas técnicas

Filter Network TrafficVulnerability ScanningPrivileged Account ManagementNetwork SegmentationLimit Access to Resource Over NetworkApplication Isolation and Sandboxing

Tecnologías afectadas (1)

Astro — @astrojs/node

CWE

Referencias

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      "value": "Astro is a web framework. In versions 9.0.0 through 9.5.3, Astro server actions have no default request body size limit, which can lead to memory exhaustion DoS. A single large POST to a valid action endpoint can crash the server process on memory-constrained deployments. On-demand rendered sites built with Astro can define server actions, which automatically parse incoming request bodies (JSON or FormData). The body is buffered entirely into memory with no size limit — a single oversized request is sufficient to exhaust the process heap and crash the server. Astro's Node adapter (`mode: 'standalone'`) creates an HTTP server with no body size protection. In containerized environments, the crashed process is automatically restarted, and repeated requests cause a persistent crash-restart loop. Action names are discoverable from HTML form attributes on any public page, so no authentication is required. The vulnerability allows unauthenticated denial of service against SSR standalone deployments using server actions. A single oversized request crashes the server process, and repeated requests cause a persistent crash-restart loop in containerized environments. Version 9.5.4 contains a fix."
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      "value": "Astro es un framework web. En las versiones 9.0.0 a 9.5.3, las acciones del servidor de Astro no tienen un límite de tamaño de cuerpo de solicitud predeterminado, lo que puede llevar a una DoS por agotamiento de memoria. Una única solicitud POST grande a un endpoint de acción válido puede colapsar el proceso del servidor en despliegues con restricciones de memoria. Los sitios renderizados bajo demanda construidos con Astro pueden definir acciones de servidor, que analizan automáticamente los cuerpos de las solicitudes entrantes (JSON o FormData). El cuerpo se almacena completamente en la memoria sin límite de tamaño — una única solicitud sobredimensionada es suficiente para agotar el heap del proceso y colapsar el servidor. El adaptador de Node de Astro ('mode: 'standalone'') crea un servidor HTTP sin protección de tamaño de cuerpo. En entornos contenerizados, el proceso colapsado se reinicia automáticamente, y las solicitudes repetidas causan un bucle persistente de colapso-reinicio. Los nombres de las acciones son detectables a partir de los atributos de los formularios HTML en cualquier página pública, por lo que no se requiere autenticación. La vulnerabilidad permite la denegación de servicio no autenticada contra despliegues SSR standalone que utilizan acciones de servidor. Una única solicitud sobredimensionada colapsa el proceso del servidor, y las solicitudes repetidas causan un bucle persistente de colapso-reinicio en entornos contenerizados. La versión 9.5.4 contiene una solución."
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  "lastModified": "2026-06-17T10:27:34.073",
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